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The Semiconductor Guidestar Laser: a Novel, Affordable, Low Swap Sodium Guidestar Laser for Adaptive Optics Tracking of Space Objects

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The Semiconductor Guidestar Laser: a Novel, Affordable, Low Swap Sodium Guidestar Laser for Adaptive Optics Tracking of Space Objects The Semiconductor Guidestar Laser: A novel, affordable, low SWaP sodium guidestar laser for adaptive optics tracking of space objects Associate Professor Celine d’Orgeville ANU Advanced Instrumentation and Technology Centre (AITC) Mount Stromlo Observatory, Canberra, Australia 8 November 2018 Outline • Adaptive Optics research @ ANU AITC • Laser Guide Star Adaptive Optics (LGS AO) 101 • 4 generations of sodium guidestar laser technologies • ANU Semiconductor Guidestar Laser program 2018 IWLR 2 Adaptive Optics Research @ ANU Advanced Instrumentation and Technology Centre (AITC) • World-leading AO research and development team: – 8-9 AO/laser/RTC instrument scientists – 4-6 postgraduates & 10-20 undergraduates – Supported by 20-25 ANU AITC engineering staff • ANU AO program: research funding & commercial contracts – Astronomy on 8-40m telescopes (e.g. ESO VLT, Gemini, Keck, Subaru, GMT, ELT): LGS AO, GLAO, LTAO, MCAO – Laser communications (e.g. DST Group, ACT Government, Quintessence Labs, NICT): horizontal, space to ground, and ground to space – Space Situational Awareness (e.g. SERC, KASI): AOI, AOTP Image Credit: Giant Magellan Telescope Organization 2018 IWLR 3 Laser Guide Star Adaptive Optics (LGS AO) 101 • Adaptive Optics – Wavefront sensor measures wavefront distortions caused by atmospheric turbulence – Deformable mirror corrects for these distortions in real time • Laser Guide Star – Provides a reference source if/where none is available Image Credit: National Astronomical Observatory Japan 2018 IWLR 4 Influence of Seeing Original image telescope diameter Example of an Iridium satellite (Strehl ratio ~ 30%) AO Imaging of space objects AOI Simulations Credit: F. Rigaut (ANU) 1.5-m 2.5-m 4.0-m 2018 IWLR 5 AO Tracking & Pushing • SERC Research Programs 1 & 4 (ANU, EOS Space Systems, Lockheed Martin) • Objective: Mitigation of debris to debris collisions using photon pressure from AO- compensated high power IR laser Image credit: D. Grosse (ANU) 2018 IWLR 6 Laser Guide Star Point Ahead Angle LEO objects: 500 km → 3200 arcsec/s 800 km → 2000 arcsec/s • Study performed by Dr Visa Korkiakoski (ANU) for AO on 1064nm laser in 2” seeing • Optimum LGS point ahead boosts AO performance in all configurations (LEO and GEO) by a factor ~2 to 3 – 2-10 arcsec typical • Optimum angle varies with object velocity & AO loop rate – Lower altitude → Greater velocity → Larger angle – Higher loop rate → Smaller angle AO Simulation credit: V. Korkiakoski (ANU) 2018 IWLR 7 2018 IWLR 8 Sodium Guidestar Laser Technology State of the Art • Review paper: d’Orgeville & Fetzer, Proc. SPIE 9909, 99090R, 2016 • Three generations of sodium guidestar lasers to date: ALFA CW dye laser @ Calar 50W CW m ode-locked solid-state laser 20W Toptica Sodium Star fibre laser Alto Observatory (Spain) @ G em ini South (Chile) @ Keck Observatory (H aw aii, USA) 1st Gen. (1990s) 2nd Gen. (2000s) 3rd Gen. (2010s) 2018 IWLR 9 Semiconductor Guidestar Laser Program • 4th gen. sodium guidestar lasers (~2020s) – Based on semiconductor laser technology – a.k.a Vertical External-Cavity Surface-Emitting Lasers (VECSEL) – a.k.a Optically Pumped Semiconductor Lasers (OPSL) • Technology demonstrated and commercialised at other l • Low component count leads to: – Small SWaP (Size Weight and Power) – Affordable procurement cost Intra-cavity doubled OPSL – Reduced maintenance cost (Image credit: Areté Associates) 2018 IWLR 10 Semiconductor Guidestar Laser Program • ANU-led project to build a prototype for use in astronomy, space, and laser communications • Project funding to date: – Government: Australian Research Council – Academia: ANU, UNSW – Observatories: AAO, GMT – Industry: EOS Space Systems, Lockheed Martin • Laser vendor: Areté Associates (USA) 2018 IWLR 11 Laser Prototype Fabrication Status 15-22U (19U shown) • Design of Laser Head and Laser ~60x80x100 cm3 Rack is nearly complete • Detailed design pending final lab Heat exchanger results and details of interfaces to EOS telescope D2A/D2B Shelf • Delivery to ANU Mount Stromlo Observatory planned in 2019 Q2 Thermal Shelves Power Shelf Processor Shelf 9” (23 cm) Optical Diagnostics Shelf 13” (33 cm) 19” (48 cm) 2018 IWLR 12 Laser Installation & Testing @ Mount Stromlo (2019) ANU/Areté semiconductor SERC Beam Transfer guidestar laser head Optics & Laser Launch Laser Launch Telescope (LLT) Telescope Elevation Fold Beam Pointing Mirror (EFM) Mirror (BPM) Corner Fold Mirror (CFM) BTO Components EOS guidestar laser on Laser Bench enclosure (3 optical benches in thermally controlled enclosure) 2018 IWLR 13 Thank you! Any questions? 2018 IWLR 114.
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